package collection;



import java.lang.reflect.Array;
import java.util.*;

public class HashSetTest {
    private static final Object o = new Object();

    public static void main(String[] args) {
        HashMap<String, Object> map = new HashMap();
        map.put("1",o);
        map.put("2",o);
        map.put("3",o);

        for (Map.Entry<String,Object> entry : map.entrySet()){
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        String[] s = {"1","2","3"};
        List<String> strings = Arrays.asList(s);
        strings.toArray(new String[0]);

    }

}
